Defluoridation using hydroxyapatite implanted lanthanum organic framework-based bio-hybrid beads

Abstract

In this exploration, promising hydroxyapatite (HAp) embedded La-BTC based metal organic frameworks (MOFs) substituted with alginate (Alg) and chitosan (CS) namely HAp–La-BTC MOFs@Alg–CS hybrid beads, were fabricated for effective fluoride retention from water. The properties of the prepared HAp–La-BTC MOFs@Alg–CS beads were analyzed with sophisticated characterization methods like TGA, DTA, SEM, XRD, FTIR, and EDAX. Batch studies of the HAp–La-BTC MOFs@Alg–CS beads towards fluoride adsorption were conducted by varying some parameters like bead dosage, interfering anions, initial adsorbate concentration, contact time, solution pH and temperature studies. The prepared bio-hybrid beads have advantages like non-toxic, renewable, biodegradable, abundant, and biocompatible nature compared with other materials. The fluoride adsorption of the bio-hybrid beads towards adsorption isotherm data was best fitted with the Langmuir model. The enhanced defluoridation capacity of HAp–La-BTC MOFs@Alg–CS beads is identified to be 4668 mgF⁻ kg⁻¹. The adsorption system was best portrayed with intraparticle diffusion and pseudo-second-order kinetic models for fluoride on the HAp–La-BTC MOFs@Alg–CS beads. The adsorption capacity of the bio-hybrid beads was compared with that of other materials reported in the literature. The fluoride adsorption mechanism of the HAp–La-BTC MOFs@Alg–CS beads was followed by electrostatic interaction and complexation. The recyclability and field study of the bio-hybrid beads was also performed and these results indicate that the developed HAp–La-BTC MOFs@Alg–CS bio-hybrid beads are regenerable and suitable in field situations.